Neuro-Ophthalmologic Monitoring in the Management of Increased Intracranial Pressure From Leaking Arachnoid Cysts

Intracranial arachnoid cysts are common incidental imaging findings. They may rarely rupture, leading to the development of subdural hygromas and high intracranial pressure (ICP). Neurosurgical intervention has been advocated in the past, but recent evidence indicates that most cases resolve spontaneously. The role of neuro-ophthalmologic monitoring in identifying the few cases that have persisting vision-threatening papilledema that justifies intervention has not been emphasized.

Original Contribution Section Editors: Clare Fraser, MD Susan Mollan, MD Neuro-Ophthalmologic Monitoring in the Management of Increased Intracranial Pressure From Leaking Arachnoid Cysts Tatiana K. Deveney, MD, Maud Lebas, MD, Remy R. Lobo, MD, Cormac O. Maher, MD, Jonathan D. Trobe, MD Background: Intracranial arachnoid cysts are common incidental imaging findings. They may rarely rupture, leading to the development of subdural hygromas and high intracranial pressure (ICP). Neurosurgical intervention has been advocated in the past, but recent evidence indicates that most cases resolve spontaneously. The role of neuroophthalmologic monitoring in identifying the few cases that have persisting vision-threatening papilledema that justifies intervention has not been emphasized. Methods: Retrospective review of 4 cases of leaking arachnoid cysts drawn from the files of the University of Michigan Medical Center (Michigan Medicine) between 2007 and 2018. Results: In 1 case, surgery was avoidable as papilledema resolved over time despite lingering imaging features of mass effect. In 3 cases, papilledema persisted with the threat of permanent vision loss, prompting neurosurgical intervention. In one of those cases, the fluid collection was thinly but extensively spread across both hemispheres without brain shift; yet, papilledema was pronounced. Emergent evacuation led to rapid resolution of papilledema and encephalopathy, but with residual optic nerve damage. Conclusions: Because constitutional symptoms and even imaging are not always reliable indicators of high ICP in leaking arachnoid cysts, neuro-ophthalmologic monitoring of papilledema is valuable in identifying the cases when neurosurgical intervention is necessary. Journal of Neuro-Ophthalmology 2021;41:e535–e540 doi: 10.1097/WNO.0000000000001143 © 2020 by North American Neuro-Ophthalmology Society A rachnoid cysts arise from fluid collections between the 2 layers of the normal arachnoid membrane (1–3). Departments of Ophthalmology (TKD, ML, JDT), Radiology (RRL), and Neurosurgery (COM, JDT), University of Michigan, Ann Arbor, Michigan. The authors report no conflicts of interest. Address correspondence to Jonathan D. Trobe, MD, Department of Ophthalmology, University of Michigan, 1000 Wall Street, Ann Arbor, MI 48105; E-mail: [e-mail] Deveney et al: J Neuro-Ophthalmol 2021; 41: e535-e540 Usually incidental neuro-imaging abnormalities, these cysts are often asymptomatic and show no progression over time. However, they can occasionally rupture, leading to subdural fluid collections called hygromas or hematomas that may cause increased intracranial pressure (ICP) (4–6). Although increased ICP in this setting usually resolves spontaneously, obviating the need for surgical intervention (1,4,7,8), there are some instances in which the fluid collections must be drained to protect against vision loss from papilledema (9). Headache and imaging evidence of enlarging or persistent extra-axial fluid collection are not reliable guides to surgical decision-making. Ophthalmologic monitoring of papilledema and its effect on vision would be more useful. We describe 4 cases to illustrate this point. CASE REPORTS Case 1 A previously healthy 4-year-old boy presented to the emergency department with 2 weeks of severe headache and 1 day of binocular diplopia. Brain computed tomography (CT) revealed a large middle and anterior cranial fossa cerebrospinal fluid collection (Fig. 1). A follow-up MRI revealed a large arachnoid cyst originating from the left middle cranial fossa with bilateral hygromas and minimal midline shift (Fig. 2A). Ophthalmologic consultation disclosed visual acuities of 20/30 in each eye, bilateral abduction deficits, a 30 prismdiopter esotropia, and bilateral papilledema. The abnormalities were attributed to increased ICP from a leaking arachnoid cyst. The patient was treated with oral acetazolamide 150 mg 3 times per day and monitored closely by ophthalmologic examination and serial imaging. Within 1 week, headache had resolved and the bilateral abduction deficits and papilledema had improved. Within 4 e535 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution Case 2 participants make frequent fast, large-amplitude head movements as the music is played. Neurological examination was unremarkable, and no imaging or treatment took place. Persistent symptoms triggered a brain CT 3 weeks later, revealing a left temporal pole arachnoid cyst with a subdural hygroma over the left temporal lobe and over both frontal and parietal lobes. Brain MRI disclosed communication between the arachnoid cyst and the subdural hygromas (Fig. 3). The subdural collection was not considered large enough to cause the patient’s symptoms, which were attributed to migraine. But, 2 weeks later, the patient developed diplopia. Ophthalmologic examination revealed visual acuities of 20/20 in each eye, a 4 prismdiopter comitant esotropia, bilateral papilledema (Fig. 4), and bilateral enlarged blind spots on automated perimetry. The abnormalities were attributed to increased ICP from a leaking arachnoid cyst. Surgical intervention was deferred in favor of close ophthalmologic and imaging surveillance. Over the next 2 months, papilledema improved slightly, but visual field abnormalities and esotropia persisted. Two months after presentation, brain CT revealed that the hygroma had converted to a chronic subdural hematoma with a new midline shift (Fig. 5A–C). Three months after presentation, the size of the left subdural hematoma was also found to be increasing (Fig. 5D). Given the persistent papilledema, visual field defects, and esotropia, together with the midline shift, he underwent drainage of the subdural hematoma through a burr hole. Brain CT performed 6 weeks after surgery showed reduction in the subdural hematoma and a stable arachnoid cyst (Fig. 6). Ophthalmologic follow-up examinations at 2 and 6 months after presentation revealed normal visual acuity and complete resolution of the ocular misalignment and papilledema (Fig. 4). A 21-year-old man with no significant medical history presented with 3 weeks of headache associated with light sensitivity, nausea, and vomiting. Symptoms began after he attended a “head-banging” rock concert in which Case Summary A healthy 21-year-old man with new headache, diplopia, and papilledema attributed to a leaking arachnoid cyst was FIG. 1. Case 1. Axial (A) and coronal (B) noncontrast brain computed tomography at presentation shows a large middle and anterior cranial fossa arachnoid cyst (arrows) and small bilateral low attenuating subdural hygromas (arrowheads). weeks after presentation, visual acuity had become normal, the abduction deficits had further improved (residual 8 prism-diopter esophoria), and the papilledema had completely resolved. Brain MRI remained unchanged. At 6 months after presentation, the abduction deficits had disappeared and eye alignment was normal. Brain MRI showed a persistent arachnoid cyst with resolution of the right portion of the hygroma and redistribution of the left portion (Fig. 2B). Case Summary A 4-year-old boy presented with dramatic clinical signs of increased ICP from bilateral hygromas attributed to a leaking arachnoid cyst. Under ophthalmologic surveillance, all clinical manifestations rapidly improved, so that surgical intervention could be safely deferred. All ophthalmologic signs eventually resolved completely over months. Brain MRI later showed improvement but not complete resolution of abnormalities. FIG. 2. Case 1. Axial T2-weighted (A) brain MRI, performed at presentation, shows a left middle cranial fossa arachnoid cyst (arrow) with a small bilateral subdural hygroma (arrowhead). Axial T2-weighted brain MRI (B1), performed 6 months later, demonstrates a persistent arachnoid cyst with disappearance of the right portion of the hygroma and redistribution of the left portion (arrow). There is left-to-right midline shift and persistent sulcal effacement (arrow) (B2). e536 Deveney et al: J Neuro-Ophthalmol 2021; 41: e535-e540 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution FIG. 4. Case 2. Fundus photographs performed 5 weeks after symptom onset show florid bilateral papilledema with hemorrhages and cotton wool spots (A); fundus photographs performed 6 months after surgical intervention show resolution of papilledema (B). FIG. 3. Case 2. Axial T2-weighted postcontrast brain MRI, performed 3 weeks after symptom onset, demonstrates a persistent middle cranial fossa arachnoid cyst (arrow) and an adjacent hygroma (arrowhead) with a slightly different signal intensity. initially followed without surgical intervention, but when papilledema and visual field defects attributable to optic neuropathy persisted for several weeks and repeat imaging disclosed a midline shift, the extra-axial fluid collection was evacuated. Ophthalmologic manifestations fully resolved over several months. The extra-axial fluid collection shrank. Case 3 A 7-year-old boy with no significant medical history had persistent headache after a presumed viral illness (1). Neurological examination was unremarkable, but brain MRI showed a large arachnoid cyst and an associated hygroma with midline shift (Fig. 7A–D). Five weeks later, he reported worsening headache and new vomiting. Ophthalmologic examination revealed bilateral papilledema. Although repeat brain imaging was unchanged, the combination of worsening headache with vomiting and papilledema prompted fenestration of the arachnoid cyst. Headache improved after surgery and visual acuity remained normal, but papilledema persisted over a 7month follow-up period. Formal visual fields were not performed because of the patient’s youth. Brain MRI performed 6 months after fenestration demonstrated an enlarging arachnoid cyst with near resolution of the subdural hygroma (Fig. 8A). Because of the persistent papilledema Deveney et al: J Neuro-Ophthalmol 2021; 41: e535-e540 and the apparent worsening of the arachnoid cyst and midline shift on MRI, he underwent placement of a cystoperitoneal shunt. At 12 months after shunt placement, the patient was symptom-free and the papilledema had resolved. Repeat imaging demonstrated a stable arachnoid cyst with a decrease in the midline shift (Fig. 8B). Case Summary A 7-year-old boy with headache attributed to a preceding viral illness had an arachnoid cyst with bilateral hygromas. Whether the headache was caused by increased ICP was uncertain. Rather than undergoing direct measurement of ICP, he was sent for ophthalmologic examination that demonstrated papilledema, precipitating cyst fenestration. Several months later, papilledema had not improved. Imaging showed enlargement of the cyst. Cystoperitoneal shunting led to resolution of papilledema and reduction in mass effect, but no change in the size of the arachnoid cyst. Case 4 A 17-year-old boy with autosomal dominant kidney disease and hypertension presented with headache, neck pain, and lethargy after an episode of head trauma and syncope. Brain MRI (Fig. 9A, B) demonstrated bilateral frontotemporal subdural hematomas without midline shift, but these abnormalities were not initially considered sufficient to explain his symptoms. Bedside ophthalmologic consultation revealed a drowsy patient with normal visual acuity and confrontation visual fields but marked papilledema (Fig. 10). The patient was too unsteady to walk. e537 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution FIG. 6. Case 2. Noncontrast brain computed tomography, performed after burr hole placement, demonstrates stable arachnoid cyst (arrow) (A) with interval evacuation of the left subdural hygroma (arrow) (B). A small volume of gas, fluid, and blood along the surgical cavity is expected in the immediate postoperative setting. fluid collections were not deemed large to cause the patient’s clinical manifestations, but ophthalmologic examination revealed marked papilledema, prompting a reinterpretation of the imaging as showing extensive FIG. 5. Case 2. Axial noncontrast brain computed tomography, performed 2 months after presentation, demonstrates a left middle cranial fossa arachnoid cyst (arrow) (A) and a left hematohygroma with recent bleeding that is layering posteriorly (arrows) (B, C). Axial noncontrast brain computed tomography (D), performed 3 months after presentation, shows an increase in the size of the collection with decreasing attenuation as the hemorrhage ages and evolves (arrow). Lumbar puncture revealed an elevated opening pressure of 55 cm H2O. Re-evaluation of the brain MRI led to the conclusion that, although the subdural fluid collections were not thick, they were extensive. The lack of midline shift was explained by the fact that the collections were bilateral, balancing each other but compressing the brain parenchyma. Bilateral surgical evacuation of these collections led to resolution of the patient’s altered mental status within 24 hours. Two months after surgery, repeat MRI disclosed resolution of the right subdural hematoma and a decrease in the left subdural hematoma (Fig. 9C). Ophthalmologic examination disclosed normal visual acuities and resolution of papilledema with mild residual optic disc pallor (Fig. 10) and visual fields showing nerve fiber bundle defects with mean deviations of 21.74 dB in the right eye and 23.95 dB in the left eye, indicative of residual optic neuropathy from the previous papilledema. Case Summary A 17-year-old boy presented with headache and altered consciousness. He underwent brain imaging that disclosed bilateral hygromas and an arachnoid cyst. The e538 FIG. 7. Case 3. Axial (A) and coronal (B) T2-weighted brain MRI, performed at presentation, demonstrates a large right middle and anterior fossa arachnoid cyst (black arrow) with an associated right subdural hygroma extending over the frontal and parietal lobes (white arrow). Postcontrast coronal T1-weighted brain MRI (C, D) suggests a connection between the arachnoid cyst and the subdural hygroma (arrows). There is left-to-right midline brain shift. Deveney et al: J Neuro-Ophthalmol 2021; 41: e535-e540 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution FIG. 8. Case 3. Axial T1-weighted postcontrast brain MRI (A), performed 6 months after cyst fenestration, demonstrates near resolution of the subdural hygroma, but increased left-to-right midline brain shift relative to the initial presentation (Fig. 7D). Because of persistent papilledema and a worsening midline shift, the patient underwent placement of a cystoperitoneal shunt. Axial T1-weighted postcontrast brain MRI (B), performed 6 months after shunt placement, redemonstrates the arachnoid cyst with a resolution of the midline shift (arrow). balanced subdural hematomas compressing the brain (10,11). Prompt drainage of both fluid collections led to immediate improvement in mental status and later complete resolution of papilledema. Imaging eventually showed reduction in the extra-axial fluid collections. There was lingering evidence of a bilateral optic neuropathy from the previously severe papilledema. DISCUSSION In these 4 cases, leaking arachnoid cysts led to extra-axial fluid collections. Ophthalmologic monitoring identified 1 case in which neurosurgical intervention could be avoided and 3 cases in which persistent papilledema justified drainage of the fluid collections. Case 1 presents an example of successful expectant management. A very young boy had a dramatic presentation with severe headache, diplopia, bilateral abduction deficits, and papilledema, considered unequivocal indicators of increased ICP. Imaging suggested that balanced extra-axial fluid collections could be compressing the brain. However, ophthalmologic monitoring showed gradual improvement of papilledema, allowing for avoidance of surgical intervention. In Case 2, surgical intervention was initially deferred, but the finding of persistent papilledema paved the way for drainage with a favorable clinical outcome. Case 3 involved a young boy whose imaging abnormalities did not worsen, but the combination of continued headache and new vomiting, coupled with persistent papilledema, tipped the decision to fenestrate the cyst. After the surgery, the headache disappeared, but the cyst was larger and the papilledema was still present, so cystoperitoneal shunting was performed to protect the optic nerves from damage. Shortly after the procedure, the papilledema resolved. Case 4 is an example of how ophthalmologic monitoring superseded brain imaging as a guide to surgical decision-making. The subdural imaging findings were not initially believed to be sufficient to cause elevated ICP. However, ophthalmologic examination revealed profound papilledema, prompting lumbar puncture that confirmed markedly elevated ICP. The profound degree of papilledema raised concern that persistently high ICP might cause further damage to optic nerve function. Accordingly, both extra-axial fluid collections were promptly and completely drained. Mental status and gait improved overnight and papilledema eventually resolved completely, although mild optic nerve dysfunction persisted. We acknowledge that there are some important limitations to ophthalmologic monitoring in this setting. Papilledema may be delayed by days to weeks after a rise in ICP because papilledema is caused by axoplasmic stasis, a phenomenon that does not promptly give rise to prelaminar optic disc swelling visible by ophthalmoscopy or optical coherence tomography (12). FIG. 9. Case 4. Axial fluid attenuated inversion recovery (A) and T2-weighted brain MRI (B), performed at presentation, demonstrates bilateral subdural hygromas (arrows). Axial T2-weighted brain MRI (C), performed 3 months after surgical evacuation, demonstrates a decrease in the size of the bilateral hygromas (arrow). Deveney et al: J Neuro-Ophthalmol 2021; 41: e535-e540 e539 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution STATEMENT OF AUTHORSHIP Category 1: a. Conception and design: T. K. Deveney, M. Lebas, R. R. Lobo, C. O. Maher, and J. D. Trobe; b. Acquisition of data: T. K. Deveney, M. Lebas, R. R. Lobo, C. O. Maher, and J. D. Trobe; c. Analysis and interpretation of data: T. K. Deveney, M. Lebas, R. R. Lobo, C. O. Maher, and J. D. Trobe. Category 2: a. Drafting the manuscript: J. D. Trobe and T. K. Deveney; b. Revising it for intellectual content: T. K. Deveney, M. Lebas, R. R. Lobo, C. O. Maher, and J. D. Trobe. Category 3: a. Final approval of the completed manuscript: T. K. Deveney, M. Lebas, R. R. Lobo, C. O. Maher, and J. D. Trobe. REFERENCES FIG. 10. Case 4. Fundus photographs performed at presentation show bilateral papilledema with associated hemorrhages (A); fundus photographs, performed 2 months after surgical evacuation, show resolution of the papilledema with resulting bilateral temporal optic disc pallor (B). Moreover, the resolution of papilledema lags weeks behind normalization of ICP, which may prompt a premature—and ultimately unnecessary—intervention (9). In the absence of papilledema, esotropia is not a reliable indicator of the need to drain extra-axial fluid collections. Caused either by a breakdown of fusion or by sixth nerve palsy owing to downward shift of the brain (13), esotropia is especially common when ICP is elevated in children and young adults (14,15). It can linger long after normalization of ICP. In Case 2, fluid drainage occurred not because of new esotropia, but because of persistent papilledema and visual field defects owing to optic neuropathy. These 4 cases underscore the value of collaboration between ophthalmologists, neuro-ophthalmologists, and neurosurgeons in determining whether and when to drain extra-axial fluid collections from leaking arachnoid cysts. As dramatic as the imaging abnormalities may appear, most cases resolve spontaneously without harm to the patient. In a small minority of cases, the identification of refractory papilledema, which may be a threat to vision, is critical in tipping the decision to operate. e540 1. Maher CO, Garton HJ, Al-Holou WN, Trobe JD, Muraszko KM, Jackson EM. Management of subdural hygromas associated with arachnoid cysts. J Neurosurg Pediatr. 2013;12:434–443. 2. Al-Holou WN, Yew AY, Boomsaad ZE, Garton HJ, Muraszko KM, Maher CO. Prevalence and natural history of arachnoid cysts in children. 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